In knitting machines or in other loop-forming machines, so-called latch needles are often employed, which for forming loops are moved back and forth in rapid succession. The latches, which are provided on the needles and pivotably supported, open and close in rapid succession. In the process, they strike the hook of the latch needle and its shank in alternation. Because of the high accelerations that the latch needles and hence the latches are exposed to, breaks of the latch shank can occur. In the past, the attempt was made by various procedures to reduce the number of latch shank breaks. For instance, European Patent Disclosure EP 0 291 687 proposes a latch of fiber-reinforced thermoplastic. However, this concept has not been successful in practice.
From German Patent DE-PS 27 14 607, it is known to damp the impact of the needle latch in the standing position by means of a special design of the longitudinal slot of the needle and thereby to avoid damage to the needle latch and to the needle itself that might occur in the standing position of the needle latch. To that end, the latch back has flanks that converge in wedgelike fashion and are capable of spreading the longitudinal slot of the needle open somewhat. However, narrow limits are set to the elastic spreading open of the needle shank cheeks.
It is also known from U.S. Pat. No. 2,596,311 to make provisions for reducing the forces of inertia that occur in the region of the needle latch by providing continuous recesses or regions of reduced wall thickness. This reference pertains to mending needles, for repairing stockings or other knitted products. The needle latch, on its end that cooperates with the needle hook, has an integrally formed-on extension that is multiple times longer than the actual latch length. To reduce its weight, it is provided with continuous recesses in the form of circular holes, or is embodied throughout with a reduced wall thickness compared to the actual needle latch. However, in these mending needles, which cannot be compared with normal needle latches, the needle latch itself is bulky, and a spoon is dispensed with.
German Patent Disclosure DE 33 31 031 A1 discloses a latch needle with a latch whose shank, in the region between its bearing point and the pivotable spoon, is provided with one or more recesses, for instance in the form of through bores. However, these recesses lead to a considerable weakening of the shank, which can cause latch shank breakages.
Another way of avoiding latch shank breakages is offered by German Published, Unexamined Patent Disclosure DE-OS 2 225 835. In it, it is proposed that the latch shank be provided with reinforcing ribs that are intended to stiffen the latch shank. The reinforcing ribs do not lead directly to a reduction in latch shank breakage.
Taking the above as the point of departure, it is the object of the invention to disclose a latch needle for a loop-forming textile machine that is intended to have a reduced tendency to latch breakage.